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#include "Qt3DSRenderClippingFrustum.h"

using namespace qt3ds::render;

SClippingFrustum::SClippingFrustum(const QT3DSMat44 &modelviewprojection, SClipPlane nearPlane)
{
    SClipPlane *_cullingPlanes = mPlanes;
    const QT3DSMat44 &modelViewProjectionMat(modelviewprojection);
    const QT3DSF32 *modelviewProjection = modelViewProjectionMat.front();

// update planes (http://read.pudn.com/downloads128/doc/542641/Frustum.pdf)
// Google for Gribb plane extraction if that link doesn't work.
// http://www.google.com/search?q=ravensoft+plane+extraction
#define M(_x, _y) modelviewProjection[(4 * (_y)) + (_x)]
    // left plane
    _cullingPlanes[0].normal.x = M(3, 0) + M(0, 0);
    _cullingPlanes[0].normal.y = M(3, 1) + M(0, 1);
    _cullingPlanes[0].normal.z = M(3, 2) + M(0, 2);
    _cullingPlanes[0].d = M(3, 3) + M(0, 3);
    _cullingPlanes[0].d /= _cullingPlanes[0].normal.normalize();

    // right plane
    _cullingPlanes[1].normal.x = M(3, 0) - M(0, 0);
    _cullingPlanes[1].normal.y = M(3, 1) - M(0, 1);
    _cullingPlanes[1].normal.z = M(3, 2) - M(0, 2);
    _cullingPlanes[1].d = M(3, 3) - M(0, 3);
    _cullingPlanes[1].d /= _cullingPlanes[1].normal.normalize();

    // far plane
    _cullingPlanes[2].normal.x = M(3, 0) - M(2, 0);
    _cullingPlanes[2].normal.y = M(3, 1) - M(2, 1);
    _cullingPlanes[2].normal.z = M(3, 2) - M(2, 2);
    _cullingPlanes[2].d = M(3, 3) - M(2, 3);
    _cullingPlanes[2].d /= _cullingPlanes[2].normal.normalize();

    // bottom plane
    _cullingPlanes[3].normal.x = M(3, 0) + M(1, 0);
    _cullingPlanes[3].normal.y = M(3, 1) + M(1, 1);
    _cullingPlanes[3].normal.z = M(3, 2) + M(1, 2);
    _cullingPlanes[3].d = M(3, 3) + M(1, 3);
    _cullingPlanes[3].d /= _cullingPlanes[3].normal.normalize();

    // top plane
    _cullingPlanes[4].normal.x = M(3, 0) - M(1, 0);
    _cullingPlanes[4].normal.y = M(3, 1) - M(1, 1);
    _cullingPlanes[4].normal.z = M(3, 2) - M(1, 2);
    _cullingPlanes[4].d = M(3, 3) - M(1, 3);
    _cullingPlanes[4].d /= _cullingPlanes[4].normal.normalize();
#undef M
    _cullingPlanes[5] = nearPlane;
    // http://www.openscenegraph.org/projects/osg/browser/OpenSceneGraph/trunk/include/osg/Plane?rev=5328
    // setup the edges of the plane that we will clip against an axis-aligned bounding box.
    for (QT3DSU32 idx = 0; idx < 6; ++idx) {
        _cullingPlanes[idx].calculateBBoxEdges();
    }
}